1. Field of the Invention
This invention relates to the field of mechanics. More particularly, this invention relates to the field of power supplies. Still more particularly, but without limitation thereto, this invention relates to the field of pneumatic, compressed gas power supplies for operation of mechanical components of missiles.
2. Description of the Prior Art
Prior power supplies for driving pneumatic servo controls and actuators have used hot gas generators which operate at gas temperatures in the 2000.degree. F. range. Such temperatures necessitate the use of steel components which reduce the efficiency of the system due to the weight of steel components. Such systems also use gases with molecular weights of around 28 which, due to their weight, have slower reaction times than would a system using a lower molecular weight gas.
Attempts to solve the limitations of prior power supplies have led to the proposal of cold gas systems pressurized to approximately 10,000 psi, however these gases are subject to adiabatic cooling factors and have relatively short operational blow down periods.
Research and development work has recently been directed to the development of a 25,000 psi compressed helium power supply. Such a high pressure system would provide increased available power over prior art systems in volume constrained missile designs. As the helium gas is released from a pressurized reservoir the remaining stored gas experiences a temperature decrease due to adiabatic cooling. The temperature drops approximately 260.degree. F. when helium expands from 25,000 psi to 2,000 psi causing higher mass flow rates, reduced operating time, and possible thermal damage to system components. Helium is a desirable operating gas, however, since its high compressibility allows higher molar densities to be achieved at a given temperature and pressure than any other known gas, thus lengthening system run time. Helium gas also has a low molecular weight which reduces control system response time.